The present invention relates to a powered support frame, especially in the form of a shield support, with a roof cap, a gob shield and a linking arrangement to join the gob shield to a ground frame, whereby the powered support frame is provided on both sides on its roof cap and on its gob shield with a laterally extensible gap sealing plate element and with at least one gap cylinder, configured as a hydraulic cylinder, to extend the gap sealing plate elements.
A powered support frame with the above features is described in DE 28 22 368 A1; the powered support frame has a laterally extensible gap sealing plate arranged both on the roof cap and on the gob shield. In each case a hydraulic positioning cylinder is provided for the lateral extension of the gap sealing element concerned.
The gap sealing elements serve not only for the sealing of a gap arising between two support frames, against rock fall from the roof and from breaking out in the case of face equipment, but also for the alignment of the individual support frames normal to the stratification between the roof and the floor on the one hand, and in the direction of face advance to their halt against a face conveyor on the other hand, so that when the face conveyor connected to their advancing mechanisms moves, the support frames can follow on a preferred line.
There is the problem, especially in support frames provided for very large seam thicknesses, for instance between 3 meters and 6 meters, that the alignment of the individual support frames is difficult to handle using the individual controls for each positioning cylinder for each gap sealing element. This problem is exacerbated if saddles and troughs occur and/or the floor undulates in the direction of the mining. In difficult mining conditions of this type the adjacent support frames must be aligned on the one hand convergent, and on the other divergent, so that the support frames can have, for instance in the region of their gob shields, a substantially smaller separation from each other than in the region of their roof caps.
The present invention therefore has the aim of improving a powered support frame as previously described, such that even with very large seam thicknesses a good alignment of the support frames to the face conveyor is simple to contrive.
In accordance with the present invention, double acting gap cylinders of the gap sealing elements are connected to a common pressure feed line and to a common return line and are activated with a uniform working pressure when the gap sealing elements are to be extended, so that all the gap cylinders, joined and communicating with each other, of the gap sealing elements on a support frame for bridging a gap to an adjacent support frame, effect a floating activation of the individual gap sealing elements until they impact on the gap sealing elements of the adjacent support frame. Owing to the connection of all the gap cylinders to a uniform pressure supply with the prescribed working pressure each gap cylinder extends the gap sealing element connected to it as far to the side until, under the prescribed pressure, this abuts the adjacent support frame or its extended gap sealing element. In this manner the work requirement for the alignment of the individual regions of individual support frames is avoided, since the support frames, owing to the floating actuation of their lateral gap sealing elements, automatically assume their optimum positions with respect to each other.
In accordance with one embodiment of the invention, in the region of the linking arrangement an additional gap sealing element is provided, so that especially with large seam thicknesses, an additional sealing and alignment facility is provided.
Possibly, several gap cylinders are provided, distributed over the extent of each gap sealing element.
For very large seam thicknesses, the gaps arising between adjacent support frames can become so large when saddles and troughs occur in the direction along the face, that the working region of an individual hydraulic cylinder of conventional design is insufficient. Therefore, according to one embodiment of the invention, for the extension of each gap sealing element a gap cylinder arrangement is provided comprising two individual cylinders arranged in series with each other, with one inner cylinder and one outer cylinder with respect to the center line of the support frame. The working range of the gap cylinder arrangement is thereby increased in an advantageous manner with respect to the alignment of the support frames to each other and to the face conveyor. Possibly, on the pressure side the inner cylinder is connected to a common pressure feed line and the outer gap cylinder to a further common pressure feed line, and on the return side the inner gap cylinder and the outer gap cylinder are connected to a common return line.
With regard to especially difficult deposit conditions, this increase in the working range can also be used to reduce the normal width of an individual support frame, and to configure the working region of the two gap cylinders positioned on either side so that the inner gap cylinders in their extended position first set the normal width of a support frame. Further to this, the possibility still exists of undertaking the necessary alignment of the support frame using the working range of the outer gap cylinder.
According to one embodiment of the invention it is proposed that the inner gap cylinder and the outer gap cylinder can be actuated by the working pressure in a time sequence, whereby a non-return valve is arranged between the pressure supply and the first, inner, gap cylinder. Thereby, the inner gap cylinder can first be extended and established in the required extended condition by the non-return valve; following this the alignment of the support frame concerned can be undertaken by controlling the outer gap cylinder by means of a separate valve arrangement.
Alternatively, the inner gap cylinder and the outer gap cylinder can be simultaneously charged with the working pressure. In this case all the gap cylinders of the currently realised gap cylinder arrangements extend over their working range depending on the gap to be bridged, so that thereby even extreme convergences or divergences can be bridged.
With regard to relieving the load due to cross forces arising on individual gap cylinders, in accordance with one embodiment of the invention the gap sealing elements are guided by means of bolt guides on an associated component of the support frame. This construction of guidance of a gap sealing element on a component of a support frame carrying it is described in outline in DE 28 53 050 C2. Here, however, a longitudinal boring, carrying the guiding bolts, is arranged in the associated component of the support frame and is thus poorly accessible and difficult to assemble. It is therefore proposed that the gap sealing elements, formed in an angle-shape, have, on arms aligned to the component of the support frame carrying them, sleeving attachments with a longitudinal boring arranged in them, which engages so as to encompass a bolt arranged on the component. Additionally, in the longitudinal boring of the attachment, a pressure spring can be arranged supporting itself between the deepest parts of the longitudinal boring and the component, engaging around the outside of the bolt and guided by the bolt against buckling.